The present invention relates to a device of the kind described in the introduction of the accompanying claim 1.
Such devices are used in many different connections for example in actuators and transport members. The devices are primarily used in the embodiment in which rotation of the shaft or the surrounding support causes displacement of the surrounding support along the shaft or the shaft through the support, respectively. It is known to adjust the speed of displacement either by adjusting the inclination angle of the rings relative to the shaft or by adjusting the rotational speed of the shaft or the support. The invention is primarily but not exclusively intended for devices of the last mentioned kind.
Generally, each device has to comprise at least three rings which are pressed against the shaft in order to obtain force equilibrium in the most suitable way. In embodiments with three rings, two of the rings are pressed in one direction against the shaft, and the third, which is usually situated between the two other rings, is pressed in the opposite direction. The bearings comprising the rings are usually mounted in bearing housings or similar members, which are displaceable in the support in a direction across the shaft and spring loaded so that the rings are urged with a pre-stress against the shaft. A complete device thus comprises a great number of parts, each of which having a relatively complicated shape and therefore being expensive to manufacture with necessary precision. The device is thus expensive and also complicated to mount.
The purpose of the present invention is to bring about a device consisting of parts which are easy to manufacture and to handle, which means that the device can be produced inexpensively and be easily mounted. According to the invention this is obtained by giving the device the characteristics which appear from the accompanying claim 1.
A device according to the invention may consist of but a few parts, which can be produced quickly and easily and with a good precision.